Posthole digger



Dec. 12, 1950 w. H. RbELFs 2,533,957

POSTHOLE DIGGER Filed Oct. 28, 1948 2 Sheets-Sheet 1 Inventor William H. Roe/f5 WW a Dec. 12, 1950 w. H. RELFs 2,533,957

POSTHOLE DIGGER Filed Oct. 28, 1948 2 Sheets-Sheet 2 Fig.2.

Fig.3

I 22 Zl I n ventor William H, Roe/f5 WWW E Patented Dec. 12, 1950 UNITED STATES PATENT OFFICE POSTHOLE BIGGER William H. Roelfs, Diller, Nebl'. Application October 28, 1948, Serial No. 57,072 2 Claims. (Cl. 255-49) This invention relates to new and useful improvements and structural refinements in post hole diggers, more specifically, post hole digg n attachments for tractors, and the principal object of the invention is to substantially absorb the torque so that the digger may be easily and conveniently manipulated by the operator.

This object is achieved by embodying in the invention what may be called a torque absorbing yoke which assures that the maximum amount of power is transmitted from the power take-oil shaft of the tractor to the auger shaft of the d'lg ger, while a minimum amount of torque is transmitted to the hand or hands of the operator.

An additional feature of the invention involves the provision of what may be called a spur on the auger shaft, this functioning in the nature of a pilot which precedes the auger and greatly facilitates feeding of the auger into the ground.

Some of the advantages of the invention lie in its simplicity of construction, in its durability, and in its adaptability to economical manufacture.

With the above more important objects and features in view, and such other objects and features as may become apparent as this specification proceeds, the invention consists essentially of the arrangement and construction of parts as illustrated in the accompanying drawings, in which:

Figure 1 is a side elevational view of the invention, the same being shown in association with a tractor;

Figure 2 is a fragmentary top plan view of the invention per se;

Figure 3 is a cross-sectional view, taken substantially in the plane of the line 3-3 of Figure 2;

Figure 4 is a fragmentary elevational view of the gear head used in the invention, together with the torque absorbing yoke, the latter being swung upwardly for convenience of illustration, and

Figure 5 is a fragmentary side elevational view of the auger shaft and spur used in the invention.

Like characters of reference are employed to designate like parts in the specification and throughout the several views.

Referring now to the accompanying drawings in detail, the invention consists of a post hole digger designated generally by the reference character ill, the same being adapted for attachment to the usual power take-off shaft l2 of a suitable tractor M, the digger I ll embodying is in its construction a gear head I6, preferably containing lubricant, and providing bearings for what may be called a driven shaft l8 and an anger shaft 2% disposed at right angles to the driven shaft it, as is shown in Figure 3.

ihe shafts i8, 25 are operatively connected together by means of suitable gearing 22 disposed in the head iii, and a pair of laterally projecting handles 26 are suitably secured to the gear head, substantially as shown.

The outer end of the driven shaft [8 is connected by means of a universal joint 25 to a driving shaft 28, the latter preferably consisting of two slidably telescoped sections 3|], 32, the section 39 being connected to the universal joint 23 while the section 32 is similarly connected by a further universal joint 34 to the aforementioned power take-off shaft l2 of the tractor I l.

Needless to say, suitable means are employed for assuring simultaneous rotation of the drive shaft sections til, 32, and the essence of novelty in the invention resides in the provision of what may be called a torque absorbing yoke, consisting of a pair of swingable arms 36 which ar provided at one end thereof with suitable bearings 38, so that they may be rotatably mounted on the aforementioned handles 24, as is best shown in Figures 2 and 4. Suitable collars M] are secured to the handles 24 adjacent the bearings 38 so as to prevent the bearings from sliding longitudinally on the handles, and it is to be noted that the arms 36 are mutually convergent and are pivotally attached at their convergent ends to a bearing block 42 which is slidably and rotatably positioned on the drive shaft section 30.

The aforementioned auger shaft 2!] is separably connected as at M to an extension 4 5, the latter carrying a screw-type auger Q8 and terminating in a pointed extremity adapted for insertion in the ground.

Another feature of novelty in the invention involves the provision of a tapered spur 52 which, as is best shown in Figure 5, is equipped with a screw-threaded shank 54 whereby it may be mounted in a radially projecting position on the auger shaft extension 66 between the pointed extremity 50 and the screw 48, is substantially as shown. Needless to say, the shaft extension 46 is formed with a screw-threaded bore so as to receive the shank 54 of the spur 52, and it is to be noted that the distance from the axis of the shaft extension 46 to the outer end of the spur as indicated at 55 is substantially less than the radius 58 of the auger screw. (See Figure 5.)

When the invention is placed in use, the spur 52 will precede the auger screw 48 as the extension shaft 46 is pushed into the ground, and the spur will thereby form a bore in the ground while the shaft extension 46 rotates,so that entry of the auger screw into the ground and subsequent feeding thereof will be greatly facilitated.

The auger screw 48 is, of course, guided into the ground by downward pressure upon the handles 24, and it is to be noted that by virtue of the yoke consisting of the arms 36 and bearing block 42, the torque transmitted by the drive shaft 28 Will be efficiently delivered to the auger, rather than reaching the hands of the operator on the handles 24. In this manner, the digger may be conveniently and easily operated, since it is not necessary to restrain the auger 48 from a tendency to rotate in a vertical plane about the axis of the driven shaft [8.

The arrangement of the arms 36 and bearing block 42 of course permits the gear head E6 to swing about the universal joint 26 in only one particular plane, that is, in a vertical plane as shown in Figure 1, it being understood that the arms 55 are pivotally attached to the bearing block 42 so that this swinging of the gear head in the vertical plane is facilitated. However, it is not necessary to align the tractor it with the hole which is to be dug, since the universal joint 34 will effectively prevent the attachment to be used in an angular relationship with respect to the center line of the tractor.

It is believed that the advantages and use of the invention will be clearly understood from the foregoing disclosure and, accordingly, further description thereof at this point is deemed un necessary.

While in the foregoing there has been shown and described the preferred embodiment of this invention, it is to be understood that minor changes in the details of construction and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as claimed.

Having described the invention, what is claimed as new is:

1. In a post hole digger, the combination of a driven shaft, an auger shaft, a gear head operatively connecting said shafts together, a drive shaft, a universal joint connecting said drive shaft to said driven shaft, a pair of laterally projecting handles secured to said gear head, a pair of swingable arms each pivoted at one end thereof to one of said handles, and a bearing block pivotally mounted at the remaining ends of said arms, said drive shaft being slidably and rotatably journaled in said bearing block.

2. In a post hole digger, the combination of a driven shaft, an auger shaft, a gear head operatively connecting said shafts together, a drive shaft, a universal joint connecting said drive shaft to said driven shaft, a pair of horizontal pivot members projecting from said gear head in opposite directions at substantially right angles to said driven shaft, a pair of swingable arms each pivoted at one end thereof to one-of said pivot members, and a bearing block pivotally mounted at the remaining ends of said arms, said drive shaft being slidably and rotatably journaled in said block.

WILLIAM H. ROELFS.

REFERENCES CITED The following references are of record in the the of this patent:

UNITED STATES PATENTS 

